Echoes of the Cold War.

From the mid-1950s the role of the Royal Observation Corps (ROC) was to monitor nuclear bomb explosions and the drift of fallout in the event of war with the USSR.  To facilitate this, 875  underground monitoring posts were built throughout the UK. Some remained operational as recently as 1991.The photograph shows the post situated on the cliff tops above Port Erroll.
The monitoring post was entered down a steel ladder in a 15 foot deep shaft (see the extra). In the underground bunker three observers used surface probes to detect the direction and power of bomb bursts. These measurements were then reported to Group HQ bunkers where the position of the burst was determined by triangulation.
Those were truly frightening times.